1. Field of the Invention
The present invention generally relates to a hand held device. More particularly, the present invention relates to a flashlight, and still more particularly to a penlight that is constructed of materials having relatively low magnetic susceptibilities. This provides the penlight of the present invention as a useful instrument in the vicinity of a magnetic resonance scanner.
2. Prior Art
The prior art is replete with various types of hand held devices such as flashlights made of metal materials that are not useful in the presence of the strong magnetic fields of a magnetic resonance scanner. Examples include U.S. Pat. Nos. 1,067,646 to Downey; 1,877,077 to Stevens; 2,459,702 to Hipwell et al.; 2,651,763 to Grimsley; 3,890,498 to Toth, Sr.; 4,203,150 to Shamlian; 4,237,527 to Breedlove; 4,286,311 to Maglica; 5,593,222 to Maglica; and 5,601,359 to Sharrah et al.
U.S. Pat. No. 4,607,623 to Bauman describes a hand held laryngoscope constructed of non-ferrous materials such as ABS with the electrically conductive portions provided by first applying a thin copper layer to the ABS followed by electroless plating and then electrolytically plating another copper layer to form a conductive layer about 0.5 to 2 mils thick. A thin layer of aluminum is subsequentially applied to the copper coating in those areas intended to be reflective. The batteries powering this device are not further described, but may be of a nickel/cadmium type commonly used for such applications. Nickel/cadmium batteries are not considered to be relatively nonmagnetic and would not be useful with the flashlight of the present invention.
U.S. Pat. Nos. 310,004 to Weston; 485,089 to Carhart; 2,282,979 to Murphy; 3,352,715 to Zaromb; 3,673,000 to Ruetschi and 4,318,967 to Ruetschi disclose anti- or non-magnetic materials in cells or batteries. Additionally, U.S. Pat. Nos. 2,864,880 to Kaye; 2,982,807 to Dassow et al.; 4,053,687 to Coiboin et al.; 4,264,688 to Catanzarite; 4,595,641 to Giutino; 5,104,752 to Baughman et al.; 5,149,598 to Sunshine; 5,173,371 to Huhndorff et al.; 5,194,340 Kasako; 5,418,087 to Klein; and 5,443,924 to Spellman relate to batteries having means for assuring that proper battery polarity is established. However, none of these patents describe power sources that are useful with the hand held device of the present invention because they either include at least some magnetic components, do not have sufficient energy density for extended use or do not have a terminal configuration similar to that of the present invention. U.S. Pat. No. 4,613,926 to Heitman et al. discloses an illuminating assembly for a magnetic resonance imaging (MRI) scanner.
There is needed a flashlight, and particularly a penlight, that is capable of withstanding conditions which exist in close proximity to the strong magnetic field of an MRI scanner. For that purpose, the penlight of the present invention is constructed largely of components having low magnetic susceptibilities. With the ever increasing use of magnetic resonance scanning to aid medical personnel during pre- and post-clinical and surgical procedures, hand held devices such as a flashlight constructed of materials that have as low a magnetic susceptibility as possible are needed to facilitate the completion of the procedure.